Metal arc lamp



Nov. l, 1932. 1--14 sTAMMREIcH METAL ARC LAMP Filed July 13, 1928 Patented Nov. 1, 1932 UNITED STATES PATENT OFFICE HANNS STAMMREICH, OF CHARLOTTENBURG, NEAR BERLIN, GERMANY, ASSIGNOR T0 PIEPMEYER & CO., KOMMANDITGESELLSGHAFT, OF KASSEL-WILHELMSHOHE, GER- MANY, A COMPANY OF GERMANY METAL ARC LAND? Application led July 13, 1928, Serial No. 292,348, and in Germany July 19, 1927i My invention concerns improvements in or relating to metal arc or metal vapour lamps. avoid certain disadvantages hitherto inherent to such lamps.

Metallic arcs have various advantages over the ordinary carbon arc and areprimarily employed when a light rich in ultra-violet rays is desirable. rIlle most usual form in this case is the mercury-quartz lamp which has the special advantage that no metal is consumed since the mercury distils and condenses inside the arc tube.

However, the energy distribution in the mercury spectrum is such that the light emitted cannot be employed for many purposes; thus it can in general not be considered for lighting purposes because it contains no red.

Although its photo-chemical action is Cer-` tainly considerable, it is, however, extraordinarily decreased by the interposition of glass in the path of the ray, the glass absorbing the greater part of the actinic rays located in the short-wave ultra-violet range. For this reason many applications in photography, for example, are impossible.

Anv attempt has been made, therefore, to employ in place of mercury, metals and spectra of which appear to be especially avourable for the particular purpose in question. Such attempts have, however, encountered technical diiculties caused by the fact that the metals, brought to melting or boiling by the arc, solidify at normal temperatures and either then and there or upon the lamp being setin operation afresh, burst the housing. Furthermore, complications arise in connection with the striking of the arc in the lamp, which, when mercury is employed may, due to its liquid nature, be elfected merelyV by tipping.

In an attempt to avoid these difficulties, while retaining mercury as the lamp filling, other metal has been added thereto. Such amalgam lamps are, it is true, capable oi operating, but do not fulfil the desired purpose, since due to the lower melting point of the mercury, almost exclusively the latter is vap, pourized in the arc tube and the spectrum of 504 the added metal appears either not at all or My invention has for its object to" very weakly only in comparison with the mercury spectrum. f

rlhe present invention makes it possible to use almost all metals in a glass. or quartz lamp by employing as the filling in the manner of an amalgam lamp a liquid, pasty, or solid alloy, or a metal mixture, of such a low melting point that the lamp container can not be destroyed, while the alloy or metal mixture is, during the operation of the lamp, separated into its components in such amanner that the low boiling or undesirable components are distilled out of the aro tube and the metal or metals desirable for the formation of theearc, remain there alone. After operation, the two components are reunited in the arc tube to form the original alloy.

In the drawing three forms of a lamp according to my invention are represented by way of example. Fig. l shows a simple form;

Fig. 2 shows another form having special features explained hereinafter; Fig. 3 shows a third form, likewise referred to hereinafter.

ln Fig. l an arc tube l has two branches 2 and 3 closed by meansof quartz pieces 4 and 1 5 through which wires 6 and 7 for the electrical current are led. The quartz pieces 4 and 5 tightly close the branches 2 and 3 so that the amalgam which is contained in two bodies 8 and 9 in the branches 2 and 3 respectively may not flow out. The upper part of the arc tube l is connected to a receiver 11 by means of a bent conduit l0.

The operation of the lamp is asollows: When the arc is struck at irst only the low boiling mercury is vapourized bythe arc and flows through conduit l() to the receiver 1l where it is condensed. The arc tube l being in communication with the receive-r or con-V densation chamber 11, the distillation of the metal does not take place consequently, as in the previous lamps, wholly inside the arc tube but the metal vapourized bythe arc distils out of the tube and condenses and remains in the receiver. The size of this receiver preferably is such that it is capable of receiving exactly the amount of metal (mercury) to be removed from the arc tube, while it causes or allows the other component metal which is intended to form the are and part of l-Ou which may distil over during operation of the lamp to flow back into the arc tube. After operation, the condensate collected in the receiver 11 is returned, by tipping, into the arc tube Where the original alloy then forms from the hot metals.

It is possible also to provide the receiver with a separate outlet which is connected to the arc tube for returning the contents of the condensation chamber to the arc tube. In this case preferably both inlet and outlet of the receiver are provided with a cock or valve. The receiver may then be of any selected or desired size.

n Figs.`2 and 3 two examples of such lamps are shown. In Fig. 2 the arc tube 12 is of a shape slightly differing from that of Fig. 1. The branches or ends are again tightly closed by quartz pieces 13 and 14 enveloping wires 15 and 16 in the same manner as in Fig. 1. A condensation chamber or receiver 17 is connected to the arc tube by a. bent con* duit or pipe 18 and by a second conduit or pipe 19. The upper portion of pipe 18 is enlarged as compared with the vertical portion; it further is somewhat inclined so that the metal distilled out from the arc tube flows easily into the receiver 17. In the lower part of vertical branch of pipe 18 a. valve 2O is provided which may close pipe 18 and therewith receiver 17 against the arc tube 12. The valve 2O consists ot' a cylindrical piece of quartz 21 in which an iron core 22 is enclosed. This quartz cylinder is movably arranged in a portion ot' enlarged diameter of the pipe 18. rlhe movement of the quartz cylinder 21 may be caused by a magnet moved along the outside ot the enlarged portion of pipe 18. p

Another valve 23 is arranged in pipe 19 likewise adapted to close receiver 17 against arc tube 12. This valve 23 is shown of a construction similar to that of valve 2O and comprises a cylindrical quartz piece 24 enclosing an iron core 25. Both valves may of course be constructed otherwise and may be operated in a different manner.

The lamp shown in Fig. 3 is constructed in its lower part much in the same manner as that of Fig. 1. It comprises again an arc tube 1 having branches 2 and 3, closing quartz pieces 4 and 5, electrical wires 6 and 7 reaching into amalgam bodies 8 and 9. A receiverl 26 is provided at the end of a vertical pipe 27 connected to arc tube 1. A branch pipe 28 leads from the lower part of pipe 27 to a point above receiver 26 to which it is connected by means of coils 29. In pipe 27 and in the portions of tube 1 and receiver 26 respectively connected thereto a double seated valve is formed consisting of a cylindrical quartz piece 30 having an iron core 31 and provided at both ends with enlarged portions 32 and 33 respectively. These portions are provided with spherical surfaces 34 and 35 respectively by which the connection from pipe 27 to either tube 1 or receiver 26 may be closed.

During the operation of the lamp the valve is open at 33/35 so that the vapours of one component of amalgam 8 and 9 are allowed to escape trom arc tube 1 through this open valve to pipe 28 and over coils 29 (which aid the cooling process) to receiver 26 where the vapours are condensed. For returning this component metal to arc tube l the valve is moved first so that it will close at its lower end and open at its upper end in order that the metal may flow from receiver 26 into pipe 27 and thence (after reverse movement of the valve) back again into arc tube 1.

The operation of the lamp shown in Fig. 2 will be clear as the valves 2O and 23 are moved independently of cach other.

I claim 1. A metal arc lamp, comprising an arc chamber containing a metal composition adapted to be used in the arc stream to produce light, a. receiver connected to said chamber, to retain one component distilled out of said metal composition, and means controlling the communication ot said receiver with said chamber.

2. A metal arc lamp, comprising an arc chamber containing a metal composition adapted to be used in the arc stream to produce light, a receiver connected to said arc chamber to retain one component distilled out of said metal composition, means arranged between said arc chamber and said receiver and adapted to control the iow of said `component on its way to said receiver, and further means to control the flow of said component back into the arc chamber.

HANNS STAMMREICH. 

